Double casing pump



y 8, 1941- A. J. STEPANOFF 2,48,312

DOUBLE CASING PUMP Filed 00v. 1958 2 Sheets-Sheet 1 Alan? J Szepazw f ATTORNEY y 1941- I A. J. STEPANOFF 2,248,312 DOUBLE CASING PUMP Filed Oct. 3, 19:53 2 sheets-sheep 2 Alexy fiiepanoff ATTORNEY Patented July 8, 1941 UNITED STATES v PATENT OFFICE DOUBLE CASING PUMP Alexey J. Stepanoif, Los Angeles, Calif., assignor to Byron Jackson 00., Huntington Park, Calit, a corporation of Delaware Application October 3, 1938, Serial No. 232,977

7 Claims.

This invention relates generally to double casing pumps, and particularly to double casing multi-stage centrifugal pumps especially adapted for pumping hot oil under relatively high pressure.

It frequently becomes necessary or desirable to provide a discharge port or bleed-off from an intermediate stage of a multi-stage centrifugal pump, in addition to 'the usual suction and discharge passages. In single case pumps no great difliculty is encountered in providing such a bleed-off. However, in double-case pumps in which the space between the inner and outer casings is filled with liquid usually at discharge pressure, the problem is more diflicult. The bleed-01f connection should, of course, be ofsuch a nature that it will not interfere with theready removal of the inner casing, and it should also .be so arranged as to permit axial movement of the inner casing relative to the outer'casing during operation of the pump to compensate for differences in expansion of the two casings when handling fluids at high temperatures;

casings which extends throughout substantially the full length of the inner casing and is adapted to be filled with liquid at discharge pressure, and in which a fluid passage is provided between an intermediate stage impeller chamber and a port in the outer casing, the passage being isolated .from the annular space between the casings,

whereby the pressure of the fluld in the passage may be different from that of the fluid in the annular space surrounding the said impeller.

chamben. a

A still further object is to provide a fluid passage between the outer casing and an interme- Because'of the differencein expansion of the two. casings, it is impractical to provide more than one annular shoulder seal between the casings.

Consequently the provision of one or more interplurality of pairs of complementary shoulders.-

It is a principal object of this invention to provide a double-casing multi-stage centrifugal pump having the usual suction and discharge passages in the outer casingcommunicating respectively with the initial and flnal stage impellers in the inner casing, and, in addition thereto, a passage in the outer casing communicating with an intermediate stage impeller chamber.

A further object is to provide a double casing multi-stage centrifugal pump in which a single shoulder seal is provided between the inner and outer casings adjacent one end of the inner casing, forming an annular space between the diate stage impeller chamber, the passage being normally isolated from the space between the two casings, and the arrangement being such as not to interfere with the insertion and removal of' the inner casing axially of the outer casing.

In a preferred form of the invention, the above and other objects are attained by the provision of aligned passages in the inner and outer cas-. ings and an extensible and retractible conduit normally bridging the annular space between the casings, the conduit being retractible to clear the annular space and permit endwise movement of the inner casing in the outer casing. The man ner in which this is accomplished will be fully understood from the following description of a preferred embodiment, taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a view, partly in side elevation and partly in longitudinal section, of a double case pump embodying the invention; Fig. 2 is an end view of the pump; and

Fig. 3 is a transverse section taken substantially on line 3-3 of Fig. 1.

Referring to the drawings, and particularly to Figs. 1 and 2 thereof, the pump is shown-as comprising an outer or pressure casing I and an inner impeller casing 2. Except as hereinafter pointed out, the construction of both the inner and the outer casing'is substantially identical with that shown in PatentNo. 2,058,017, to Aladar Hollander dated October 20, 1936, towhich reference may be made for a more detailed'dlsclosure of the cross-ov'ers-between thevarious impeller chambers. It will be sufficient to state here that the annular space between the inner and outer casings is divided into a suction area 3 and a pressure area 4 separated by a shoulder seat 5. The, pressure casing I is provided with a suction nozzle 6 having a suction passage 1 communicating with the suction area 3 and the first stage impeller 8, and a discharge nozzle 9 having a discharge passage communicating with the the exterior of the pressure casing'l and an intermediate stage impeller cavity, the following construction is provided. An auxiliary nozzle I5 is formed on the casing I, either as an integral part thereof or by welding as at IB in Figure 3. The nozzle l5 comprises a portion l'l extending radially outwardly of the casing I, and an upwardly directed branch l8, the aXes of the two portions lying in a radial plane through the impeller cavity 29 with which the nozzle communicates. I shown in Figures 1 and 2, the vertically extending portion I8 is parallel to but offset slightly from the suction nozzle 6 and discharge nozzle 9. It will also be observed that the bolting faces of the flanges of all three nozzles lie in a common horizontal plane to facilitate the connection of piping thereto.

The radially extending portion ll of the nozzle i5 is provided with stepped ,bores 22 and 23 in which is slidable a ported plug 24 having correspondingly stepped cylindrical surfaces 25 and 25.

A port 21 is formed in the plug 24, the inner portion thereof extending radially and being aligned with a port 28 formed in a boss 29 projecting out- Wardly from the impeller cavity 20. The outeraligned with the passage 30 in the nozzle portion I8 when the plug 24 is in operative position.

Suitable packing 32 is provided between the shoulders formed on the plug and in the bore of the nozzle portion I! to prevent leakage of high pressure fluid around the plug from the annular space 4, and a gasketin the form of a soft iron wire ring 33 is provided between the inner end of the plug and the outer end of the boss 29 to prevent leakage from space 4 into the bore 21 or 28. It will be observed from Fig. 3 that the inner end of the plug 24 projects into an annular recess in the outer end of the boss 29, the recess being of substantially greater diameter than the inner end of the plug to permit axial movement of the inner casing 2 relative to-the plug while maintaining the seal. Such movement of the inner casing occurs as the result of differential .expansion between the inner and outer casings under the influence of temperature changes, and is unrestrained by the mounting of the inner casing in the outer casing with only a single pair of abutting annular shoulders between the casings as indicated at 5 in Fig. 1.

In order to provide for insertion and removalof the impeller casing, the plug 24 is retractible outwardly into the nozzle portion ll. Means are provided, however, for forcing the pluginwardly to compress the packing 32 and 33 and for holding the plug in such position. A bolt 34 has a rounded inner end engageable with a socket 35 in the outer end of the plug 24, the bolt being in screw-threaded engagement with an end plate 36 bolted to the outer end of the nozzle portion II. The outer end of the bolt is squared at 31 for the application of a wrench, it being understood that upon rotation of the bolt in the proper direction the plug 24 will be forced inwardly into abutting the plug 24 being manipulable in the bore 22 upon removal of the cap 36.

The application of-any considerable force to the bolt 34 would have a tendency to distort the impeller casing, and in order to prevent such distortion a tensionstud assembly, generally indicated-at 42 in Figure 3, is provided on the outer casing diametrically opposite the nozzle I 5. This assembly comprises a bolt 43 threadedly engaging a block 44 welded into an opening in the outer casing. The inner end of the bolt is rounded and is received in an axially elongated socket 45 in the outer periphery of the impeller casing and the outer end of the bolt is squared at 45 for the application of a wrench. A cap 41 is threaded 'over the outer end of the bolt and issealed to the block 44 by a gasket 48.

The plug 24 is maintained in properly oriented position within the bore 22 with the port 21 in alignment with the port 30 by means of a pin and slot arrangement generally indicated at 5|. A narrow, elongated slot 52 is formed in the periphery of the plug and receives the inner end of a pin 53 threaded through the wall of the nozzle portion H. A cap 54 is threaded over the outer end of the pin and is sealed to the nozzle by a gasket 55.

From the foregoing description of a preferred form of the invention, it will be apparent that I have provided a novel and very effective 'arrangement for establishing communication between the exterior of a double casing pump and an intermediate stage impeller cavity. My novel construction avoids-the necessity of providing shoulder seals on opposite sides of the selected intermedi to stage volute to isolate the annular space at that point from the annular space surrounding the remainder. of the impeller casing.

For this reason less departure from standard double casing pump construction is required in order to provide a bleeder outlet from an intermediate stage. Furthermore, as pointed out in the introductory remarks, the provision of a plu-= rality of shoulder seals is not practicalbecause of relative endwise movement between the casings due to difierences in expansion. 7

It will be appreciated that the construction shown in Figure 3 is not limited in its application it may be applied to any stage of a multi-stage double casing pump, irrespective of the'number of stages employed.

It will be apparent also that my improved connection is equally capable of use as an inlet to any desired stage. It is within the contemplation of this invention that a second connection identical with that shown in Fig. 3 may be provided in connection with another intermediate stage, whereby a' portion of the discharge from the higher of the two intermediate stages may be circulated outside the pump for whatever purpose desired and any part or all returned to the pump by way of the lower of the two intermediate stages.

It is also contemplated that the connection described above may be employed in pairs, one as an outlet and one as an inlet, to provide external cross-overs between adjacent-stage impellers. Such an arrangement would permit a substantial reduction in the diameter of the impeller casing and of the outer casing.

. annular space between said casings, substantially While I have described in detail a preferred embodiment of the invention, it is to be understood that it is not to be limited to the details herein set forth, but the invention is of the full scope of the appended claims.

I claim: 4 I

1. In a double casing centrifugal pump, an outer casing, an inner casing therein and circumferentially spaced therefrom to define an radially extending aligned fluid passages in said inner casing and said outer casing, means forming a fluid-tight seal between the adjacent ends of said fluid passages, means adjustable relative to said outer casing for applying pressure inwardly in the direction of the axis of said fluid passages to maintain said seal, said pressure tending to distort said inner casing in an axial plane thereof, and means adjustably mounted between said inner and outer casings on the diametrically opposite side of said inner casing from said fluid passages, for applying pressure opposing said first pressure-applying means to prevent distortion of said inner casing by said first pressure-applying means. i

2. In a double casing pump, the combination of: an inner casing; one or more pumping elements therein; an outer casing surrounding said inner casing and having fluid inlet and outlet passages extending therethrough, said inner casme: having inlet and outlet passages communicating respectively with the inlet and outlet passages through said outer casing; at least one of said passages in said outer casing being formed at least partially in a conduit member movably mounted in said outer casing and having a sealing surface thereon extending substantially parallel to the longitudinal axis of said outer casing; said inner casing having a sealing surface opposing said first-named sealing surface and surrounding one of the fluid passages through said inner casing; said sealing surfaces being adapted to be disposed in sealing relation to each other upon relative movement between said conduit member and said outer and inner casings in a 4 direction transverse to the longitudinal axis of said inner casing, and said sealing surfaces be-v ing movable relative to each other in a direction parallel to the axis of said inner casing while I maintaining the sealing relation between said surfaces.

3. In a double casing pump; the combination of an inner casing; one or more pumping elements therein; an outer casing surrounding said inner casing and having fluid inlet and outlet passages extending therethrough, said inner casing having inlet and outlet passages communicating respectively with the inlet and outlet passages through said outer casing; and means interconnecting a fluid passage in the outer casing in fluid-tight relation to the corresponding fluid passage in the inner casing, said means comprising a conduit member movably mounted in one of said casings, said conduit member and the other of said casings having opposed sealing surfaces extending parallel to the axis of said inner casing and adapted to be disposed in abutting fluid-tight relation to each other upon movement of said conduit member relative to the casing in which it is mounted, said sealing surfacesbeing movable relative to each other in a direction parallel to the axis of said inner casing while maintaining said fluid-tight relation.

4. In a double casing pump, the combination of: an inner casing; one or more pumping elements therein; an outercasing surrounding said inner casing and having fluid inlet and outlet passages therethrough, said inner casing having fluid inlet andoutlet passages communicating respectively with the passages through said outer casing; and means interconnecting at least one of said fluid passages in said outer casing in fluidtight relation tovthe corresponding passage in said inner casing, comprising a conduit member slidably mounted in said outer casing and having a fluid passage therein communicating at one end with a fluid passage in the outer casing,

and having its opposite end aligned with a fluid.

passage in the inner casing, said conduit member and said inner casing having opposed parallel sealing surfaces extending parallel to the axis of said inner casing, means for moving said conduit member toward said inner casing to dispose said sealing surfaces in abutting fluid-tight relation to each other, said sealing surfaces being constructed and arranged to permit substantial relative movement therebetween in a direction parallel to the axis of said inner casing while maintaining said fluid-tight relation.

5. A double casing pump as set forth in claim 4, in which said means for moving said conduit member comprises cooperating threaded members associated respectively with said conduit member and said outer casing. 6. A double casing pump as set 4, in which the fluid passage in said conduit member extends laterally through a side wall thereof in registry with a corresponding fluid passage in said outer casing, the oumr extremity of said conduit member being closed, and in which said means for moving the conduit member comprises a threaded member engageable with the closed outer extremity of the conduit member and having threaded engagement with means on said outer casing.

'7. A double casing pump as set forth in claim 2, in which the sealing surfaces on said conduit member and said inner casing comprise annular plane surfaces, one of which is disposed at the base of a recess in the corresponding member, the

width of said recess exceeding the width of the other 'of said sealing surfaces by an amount sufficient to permit substantial relative movement be tween said surfaces in a direction parallel to the axis of said inner casing.

J. STEPANOFF.

forth in claim 

